Study: Running Economy Improves After 4 Weeks in Vibram FiveFingers

The running economy of experienced runners improved significantly after they followed a four-week process of gradually running more in Vibram FiveFingers, according to a study published in the Scandanavian Journal of Medicine & Science in Sports. In addition, the study found, at the end of the four-week familiarization process, the runners were much more economical in Vibram FiveFingers than in conventional running shoes.

Running economy is a measure of how efficiently you use the oxygen you breathe in when running. If all other factors are the same between two runners, the one with better running economy will be faster. Put another way, if all other factors in your running remain the same, then improving your running economy will make you faster.

The study looked at what happened to the running economy of 15 experienced runners as they gradually got used to running in Vibram FiveFingers. One strength of the study is that the subjects were highly trained, with an average 1500-meter PR of 4:00, which is equivalent to about a 4:17 mile. Their level of running ability is significant because such runners are likely to already do many of the things, such as regular speedwork, that have been shown to improve running economy. So any gains in running economy in such a short time likely indicate something significant is happening beyond the normal gains in fitness to be expected from training.

At the beginning of the study, researchers at Dublin City University measured the subjects' running economy twice, once while the subjects ran in conventional training shoes (the Asics Nimbus) and once in what lead researcher Joe Warne calls the "classic" Vibram FiveFingers. "I wanted something with the original and seamless 3-millimeter sole," Warne told Runner's World Newswire about his choice of Vibram FiveFingers as the best way to simulate barefoot running while providing the runners protection from surface abrasion. (Vibram did not fund the study.)

None of the runners were used to running in Vibram FiveFingers. When their running economy was first measured, they were slightly more economical (1.05%) in Vibram FiveFingers than when wearing the Nimbus. This finding is consistent with other studies showing slightly better economy in minimalist shoes during short tests in a lab; the difference is usually attributed to the lighter weight of minimalist shoes. In this study, running economy was tested at paces of 11 kilometers per hour and 13 kilometers per hour. Warne points out that, for these runners, that's the pace they might run on a normal, easy 30- to 45-minute run.

Over the next four weeks, the runners gradually introduced the Vibram FiveFingers into their shoe rotation. They started with two 15-minute runs the first week, and worked up to three or four 30-minute runs by the fourth week. Warne told the runners nothing about how to run differently in the Vibram FiveFingers, nor did he have them do running form drills. The only additional exercises they did in conjunction with the study were calf raises and rolling their heels on a golf ball to address standard aches and pains associated with transitioning to minimalist shoes. "The rationale for adopting this approach was to evaluate 'natural' rather than 'enforced' changes as a result of [simulated barefoot running]," Warne wrote in the study.

After four weeks, Warne remeasured the subjects' running economy. He found two noteworthy changes: First, the runners had become much more economical in the Vibram FiveFingers. While running at the same paces as at the beginning of the study, they were just more than 8% more economical in the FiveFingers than they had been in the same shoes at the beginning of the study.

Second, whereas at the beginning of the study the runners were just a bit more economical in Vibram FiveFingers compared to running in the Nimbus, by the end of the study that difference had increased to 6.9%.

Warne thinks the difference in running economy when wearing Vibram FiveFingers compared to the Nimbus after four weeks is too big to attribute solely to the FiveFingers' weight and design. "[B]iomechanical changes to running technique that occur over time such as a greater plantar flexion angle and minor changes in [stride frequency] would appear to be key contributory factors," the study states. In addition, Warne told Runner's World Newswire, "I haven't yet found any significant correlations between running form and changes in running economy as of yet (I am on my 3rd study currently), which leads me to assume that the most remarkable changes are related to neuromuscular control of running."

Warne is careful to point out that the subjects were running at what for them is an easy, relaxed pace when their economy was tested. As such, whether their running economy would improve so dramatically in Vibram FiveFingers at race pace is unknown. This study, like most other involving how people run differently in minimalist shoes, found that the runners increased their turnover and shortened their stride when they switched from the Nimbus to FiveFingers. Given that most runners increase stride rate and stride length when racing compared to running easily, it's reasonable to ask whether the gains in running economy in Vibram FiveFingers could be preserved over the course of a race.

This study didn't find a crossover effect between minimalist shoes and conventional modes; that is, the gains in running economy when wearing Vibram FiveFingers didn't seem to lead to greater efficiency when wearing the Nimbus. Nonetheless, Warne told Runner's World Newswire, "I absolutely believe that once some degree of barefoot or simulated barefoot running training is included on several occasions per week, that we will see carryover benefits with regard to running form, etc.

"My second study (in review) found significant reductions in plantar forces in both Vibram FiveFingers and [conventional running shoes] following a similar four-week intervention. Again, this wasn't related to techniques as far as I am aware but again due to neuromuscular control."

At the same time, Warne points out, "It's also key in this regard to remember that for the present study we didn't include any feedback on running form or drills, etc. Everything was natural, which suggests even though we do see changes in running form and running economy, the changes are optimized whilst barefoot or [in Vibram FiveFingers] and cannot be applied to anywhere near the same degree if remaining shod."

Scott DouglasScott is a veteran running, fitness, and health journalist who has held senior editorial positions at Runner’s World and Running Times.

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